Clamping jaw pneumatic adjusting device and method

Abstract

According to the clamping jaw pneumatic adjusting device and method, an air cavity structure with a built-in air channel and an air bag is formed by combining a base layer and a channel layer, and the air cavity structure is fixed to the inner side of a clamping jaw in a bonding mode. According to the method, on the basis of a kinematic model between airbag deformation and object posture, a specific airbag is driven by an air source to generate controllable deformation, so that the posture of a clamped object is actively adjusted. The multi-degree-of-freedom micro-operation which is low in cost and easy to integrate and does not change a clamping jaw body is achieved through a simple attaching type structure and pneumatic driving.

Description

A pneumatic adjustment device and method for grippers Technical Field

[0001] This application relates to a pneumatic adjustment device and method for grippers, belonging to the field of precision manufacturing technology. Background Technology

[0002] In the field of precision manufacturing technology, two-finger grippers, as core components of robot end effectors, have become key equipment in scenarios such as electronic semiconductor packaging, precision assembly of 3C products, and biomedical sample handling due to their advantages of simple structure and rapid response. As industrial automation develops towards flexible manufacturing, downstream applications are placing higher demands on the gripper's functionality. It not only needs to achieve stable gripping but also needs the ability to adjust the object's posture with multiple degrees of freedom while gripped, in order to adapt to complex and precise operational tasks.

[0003] Currently, the main technical approaches to achieving micro-manipulation with a two-finger parallel gripper include the following three:

[0004] First, the gripper body integrates a multi-degree-of-freedom mechanical structure. By integrating additional drive units, such as micro servo motors, into the gripper fingers, the gripper itself possesses degrees of freedom for rotation and deflection. Existing research has proposed a five-degree-of-freedom tactile two-finger gripper with drive units integrated into the finger roots and knuckles, as well as a two-finger micro-manipulation gripper that uses parallel drives to achieve lifting and rotation. However, this approach typically results in complex mechanical structures, cumbersome control logic, and high manufacturing costs. Furthermore, highly integrated mechanical components are prone to wear and jamming during frequent micro-movements, affecting system reliability and lifespan.

[0005] Second, adaptive posture adjustment is achieved using flexible structures at the fingertips or finger bodies. This method compensates for posture errors through the deformation of flexible materials, such as using grippers with a rigid base and a flexible fingertip composite structure. While flexible structures can provide a certain degree of adaptability, their deformation is usually passive or limited to a small range of actuation, which has obvious limitations: First, the flexibility of the material limits its load-bearing capacity; second, the deformation and recovery dynamic response of flexible bodies is slow, making it difficult to achieve fast and precise posture control; in addition, flexible materials are prone to fatigue aging during long-term cyclic use, affecting service life and accuracy retention.

[0006] Third, an external motion platform can be used to coordinate the movement of the gripper. The gripper is mounted on a micro-motion platform or robotic arm with high-precision positioning capabilities, and the object's pose is adjusted through the platform's movement. While this method offers high degrees of freedom and positioning accuracy, it suffers from complex system integration and extremely high costs. Furthermore, the installation, calibration, and coordinated control of multiple systems are difficult, and maintenance is cumbersome, hindering its widespread application in compact industrial settings or those requiring rapid deployment.

[0007] Currently, existing technologies for endowing two-finger grippers with micro-manipulation capabilities generally face problems such as high cost, system complexity, limited reliability, insufficient dynamic performance, or low integration. Therefore, there is an urgent need to find a technical solution that is simple in structure, low in cost, easy to integrate, and can achieve controllable multi-degree-of-freedom micro-manipulation. Summary of the Invention

[0008] The purpose of this application is to overcome the shortcomings of the prior art and provide a pneumatic adjustment device and method for grippers, which solves the problems of complex structure, high manufacturing cost, difficulty in rapid integration into existing grippers, and decreased reliability due to the integration of mechanical drive units when giving them micro-operation capabilities.

[0009] To achieve the above objectives, this application employs the following technical solution:

[0010] In a first aspect, this application provides a pneumatic adjustment device for a gripper. The device comprises an air cavity structure formed by combining a base layer and a channel layer. The air cavity structure includes several air channels and several air bladders connected by the air channels. The air bladders are disposed on the inner side of the gripper's fingers and are used to contact and push the gripped object. The air channels are connected to an air source through air pipes, and the air source is used to supply air to the air cavity structure. The air bladders undergo controllable deformation under the drive of the air source, and can coordinately adjust the posture of the gripped object relative to the gripper.

[0011] In conjunction with the first aspect, furthermore, each finger clip has at least three airbags on its inner side, arranged along the length of the finger clip.

[0012] Furthermore, among the airbags arranged along the length of the finger, there is at least one support airbag located in the middle region and adjustment airbags located on both sides of the support airbag.

[0013] Furthermore, the airbag is attached to the inside of the gripper's fingers by an adhesive method.

[0014] Furthermore, the channel layer is made of a flexible elastic material, including silicone.

[0015] Furthermore, the device includes a control unit, which is communicatively connected to an air source and is used to control the air source to supply air to the airbag according to the gripper's target posture command.

[0016] Secondly, this application provides a pneumatic adjustment method for a gripper, comprising the following steps:

[0017] Fix the pneumatic adjustment device of the gripper to the inside of the gripper's fingers;

[0018] Control the grippers to hold the object so that the object's surface comes into contact with the airbag;

[0019] Based on the target posture set for the object, the control unit controls the air source to selectively supply air to the airbag, causing the airbag to deform and push the object to adjust to the target posture. The control unit has a kinematic model that pre-stores the mapping relationship between the airbag deformation and the object posture.

[0020] In conjunction with the second aspect, the control unit further obtains the target deformation required for each airbag based on the target posture and kinematic model; generates a gripper target posture command based on the target deformation, controls the air source to output the corresponding air pressure, and drives the corresponding airbag to deform to the target deformation.

[0021] Compared with the prior art, the beneficial effects achieved by this application are as follows:

[0022] This application provides a gripper pneumatic adjustment device and method, which constructs a fine-tuning execution layer without changing the gripper body by directly attaching a flexible air cavity structure with air passages and air bags to the inner side of an existing gripper.

[0023] Based on the kinematic model between airbag deformation and object posture, the air source is controlled to inflate multiple airbags on the inner side of the gripper in combination, so that the airbags deform in coordination to actively push the object, thus realizing precise adjustment of the posture of the gripped object.

[0024] This application provides a pneumatic adjustment method for grippers, which avoids the problems of bloated structure and high cost caused by integrating complex drive mechanisms inside the grippers. It also breaks through the limitation that flexible materials can only passively adapt and lack active control capabilities. With a low-cost and easy-to-deploy attachment method, it provides ordinary grippers with precise multi-degree-of-freedom micro-manipulation capabilities. Attached Figure Description

[0025] Figure 1 is a schematic diagram of the structure of a gripper pneumatic adjustment device provided in an embodiment of this application;

[0026] Figure 2 is an exploded view of a gripper pneumatic adjustment device provided in an embodiment of this application;

[0027] Figure 3 is a comparison diagram of the static state and the inflated state of a gripper pneumatic adjustment device provided in an embodiment of this application;

[0028] Figure 4 shows the simulation control platform provided in the embodiment of this application, where a is a physical diagram of the simulation control platform and b is the air chamber module of the simulation control platform;

[0029] Figure 5 shows the attitude control of the clamped object under the simulation control platform provided in the embodiment of this application, where a is the triangular motion trajectory of the end of the clamped object, b is the square motion trajectory of the end of the clamped object, c is the figure-eight motion trajectory of the end of the clamped object, d is the airbag deformation displacement corresponding to the triangular motion trajectory, e is the airbag deformation displacement corresponding to the square motion trajectory, and f is the airbag deformation displacement corresponding to the figure-eight motion trajectory.

[0030] Figure 6 is a schematic diagram of the actual installation location of the gripper pneumatic adjustment device provided in the embodiment of this application;

[0031] Figure 7 is a diagram of the actual working effect of the gripper pneumatic adjustment device provided in the embodiment of this application, where a is the left posture adjustment of the gripped object, b is the right posture adjustment of the gripped object, c is the front posture adjustment of the gripped object, and d is the rear posture adjustment of the gripped object.

[0032] Figure 8 shows the repeatability test results of airbag deformation provided in the embodiments of this application;

[0033] Figure 9 is a schematic diagram of the control accuracy of the gripper pneumatic adjustment device provided in the embodiment of this application;

[0034] Figure 10 is a physical illustration of the flexibility of the gripper pneumatic adjustment device provided in the embodiment of this application;

[0035] Figure 11 is a schematic diagram showing the relationship between the maximum deformation height of the airbag and the hysteresis of the driving air pressure provided in the embodiments of this application.

[0036] In the diagram: 1. Basal layer, 2. Channel layer, 3. Airway, 4. Air sac, 5. Trachea. Detailed Implementation

[0037] The technical solution of this application will be described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the embodiments and specific features in the embodiments are detailed descriptions of the technical solution of this application, rather than limitations thereof.

[0038] Example 1:

[0039] This embodiment provides a gripper pneumatic adjustment device, as shown in Figures 1 and 2. The device employs a double-layer structure design, including a base layer 1 and a channel layer 2, with the two layers bonded together with silicone to form a closed air cavity. This air cavity mainly consists of an air passage 3 and an airbag 4. The airbag 4 is the main working unit of the gripper pneumatic adjustment device, deforming under the drive of gas input through the air passage 3, thereby pushing the object to change its posture.

[0040] The gripper pneumatic adjustment device is also equipped with an air pipe 5. One end of the air pipe 5 is fixed to the air passage hole with silicone adhesive, and the other end is connected to an air pump. The entire gripper pneumatic adjustment device can be firmly fixed to the end of the gripper with silicone.

[0041] Example 2:

[0042] This embodiment uses a two-finger parallel gripper as an example, and provides the following pneumatic adjustment process:

[0043] The pneumatic electric pump outputs gas, which is delivered to the air bag 4 through the air passage 3. The air bag 4 inflates under the action of air pressure, thereby pushing the object held by the gripper to change its posture.

[0044] As shown in Figure 3, five airbags are symmetrically arranged inside the parallel grippers, totaling ten airbags per pair of grippers. During operation, the support airbag in the middle of the grippers inflates to support and secure the object being gripped. The remaining eight airbags work together to adjust the object's posture through coordinated deformation, achieving precise adjustment.

[0045] Figure 6 shows a schematic diagram of the actual installation of the gripper pneumatic adjustment device on the two-finger parallel gripper.

[0046] To achieve precise control of airbag deformation, this application employs a control strategy combining offline calibration and online lookup tables, based on a kinematic model relating airbag deformation to object posture. First, according to the kinematic model established in this application, all possible target object postures are traversed. By solving the model, the deformation height combinations of the eight surrounding airbags required to achieve each posture are obtained, forming a "target posture-airbag height" lookup table. Simultaneously, the steady-state deformation height of each airbag under different input air pressures is experimentally measured, establishing a "pressure-deformation height" mapping table. The inflation and deflation processes are calibrated separately, considering the driving air pressure hysteresis characteristics shown in Figure 11. Both lookup tables are stored together in the control unit.

[0047] In actual operation, the control unit performs the following steps:

[0048] First, the system receives the target posture command for the object; second, it queries the "Target Posture - Airbag Height" table to obtain the target deformation height required for each airbag; then, depending on whether the current operation is inflation or deflation, it looks up the corresponding target air pressure value in the "Air Pressure - Deformation Height" mapping table; finally, it controls the air source to output the corresponding air pressure, driving each airbag to deform collaboratively to the target height, thereby adjusting the object to the preset posture.

[0049] Since the table lookup operation only takes microseconds, while the airbag mechanical response time is about 0.3 seconds, as shown in Figure 11, this control strategy can meet the requirements of real-time applications.

[0050] To verify the feasibility, working range, and movement flexibility of the gripper pneumatic adjustment device in controlling the posture of the gripped object, as shown in Figure 7, where a, b, c, and d represent the basic left, right, front, and back posture adjustments of the gripped object, this application further analyzes the simulation results and determines the required deformation height of each airbag when achieving complex target postures.

[0051] The simulation process is as follows:

[0052] As shown in Figure 4a, the constructed simulation platform represents the positional relationship between the gripper and the object being gripped. The pneumatic adjustment device for the gripper described in this application is placed on both sides of the gripper, forming the upper air chamber module and lower air chamber module shown in Figure 4b. Figure 4b shows four platforms composed of these two air chamber modules and the tool contact surface, labeled from top to bottom as the upper static motion platform, upper motion platform, lower motion platform, and lower static motion platform. Setting parameter l u1 l u2 l u3 l u4 l l1 l l2 l l3 and l l4 These figures represent the aerodynamic deformation heights of the four airbags in the upper and lower air chamber modules, respectively. The two centrally located airbags serve as support pivots for the upper and lower surfaces. The relationship between the aerodynamic deformation heights of the eight airbags and the coordinates of the end-target is analyzed as follows:

[0053] The coordinates of each platform are expressed in the form of matrix M:

[0054]

[0055] As shown in Figure 4, the positions of each platform are represented as follows:

[0056]

[0057]

[0058]

[0059]

[0060] In the formula, Indicates the position of the static platform. Indicates the position of the lower motion platform. Indicates the position of the static platform. 'b' represents the position of the upper motion platform, and 'b' represents the initial deformation height of all eight airbags. 2a represents the distance between each peripheral airbag and the central support airbag along the x-axis and y-axis; H represents the distance between two adjacent peripheral airbags; H represents the distance between the upper air chamber module and the lower air chamber module.

[0061] Assume the spatial coordinates of any end of the crawling tool are:

[0062]

[0063]

[0064] In the formula, The X-axis spatial coordinates of the end of the grasping tool. The Y-axis spatial coordinates of the end of the grabbing tool. The Z-axis spatial coordinates are the ends of the grasping tool.

[0065] This indicates the deflection angle of the grasped tool along the z-axis. This represents the deflection angle of the grasped tool along the y-axis. The final position of the lower motion platform is obtained by performing a planar coordinate transformation using the rotation matrix. :

[0066]

[0067] The final position on the exercise platform is :

[0068]

[0069] Where the rotation matrix , for:

[0070]

[0071]

[0072] The final relationship between the airbag deformation height and the tilt angle of the grasped object is shown below:

[0073]

[0074]

[0075] The deformation height relationship of each peripheral airbag is as follows:

[0076] i=1,2,3,4

[0077] i=1,2,3,4

[0078] To solve this system of nonlinear equations, Newton's descent method is used for forward kinematics solving:

[0079] (0 <w≤1)

[0080] In the formula, As a decreasing factor, , Current pose parameters Below is the deviation between the calculated length of the pneumatic module and the actual length of the pneumatic module, where... , in The deviation between the height of the four airbags and the target height, The deviation between the height of the next four airbags and the target height.

[0081] ,

[0082] The Jacobian matrix is ​​obtained by differentiating the function of airbag deformation. .

[0083]

[0084] Indicates adjustment At that time, the degree of impact on each of the four air sacs in the upper air chamber;

[0085] Indicates adjustment At that time, the degree of impact on each of the four air sacs in the lower air chamber;

[0086] Indicates adjustment At that time, the degree of impact on each of the four air sacs in the upper air chamber;

[0087] Indicates adjustment At that time, the degree of influence on each of the four air sacs in the lower air chamber.

[0088] Its final condition is:

[0089]

[0090]

[0091] In the formula, In the k-th iteration The change , It is the smallest integer greater than 0.

[0092] The kinematic model was solved using Matlab to determine the correspondence between the position and orientation of the gripper's end effector and the height of each airbag. Based on this relationship, a pneumatic array control program was developed to manipulate the object held by the gripper to the target position.

[0093] As shown in Figure 5, simulation verification demonstrates that the two-finger parallel gripper can stably control the end of a cylindrical object to achieve various trajectories, including triangles, squares, and figure-eights. Figures a, b, and c in Figure 5 show the triangular, square, and figure-eight trajectories achieved at the end of the object while holding it, with the gripper's pose unchanged. Figures d, e, and f in Figure 5 show the required deformation heights of the surrounding airbags for achieving these three trajectories, and the airbag operation is ultimately controlled according to these deformation heights.

[0094] Figure 10 shows a schematic diagram of the actual control of the gripper pneumatic adjustment device provided in this application to complete a square motion trajectory of the gripped object. As shown in Figure 11, the gripper pneumatic adjustment device basically reaches the maximum deformation displacement of the airbag within 0.3s. The gripper pneumatic adjustment device shown in Figure 8 has good and stable repeatability. The gripper pneumatic adjustment device shown in Figure 9 can achieve an adjustment accuracy of 1°.

[0095] The pneumatic adjustment device for grippers provided in this application is inexpensive, widely applicable, and the pneumatic adjustment method for grippers does not require complicated procedures. It can flexibly adjust the position and posture of the gripped object with multiple degrees of freedom to achieve the target position and posture.

[0096] The above description is only a preferred embodiment of this application. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of this application, and these improvements and modifications should also be considered within the scope of protection of this application.

Claims

1. A pneumatic adjustment device for grippers, characterized in that, The device consists of an air cavity structure formed by the combination of a base layer (1) and a channel layer (2). The air cavity structure includes several air channels (3) and several air bladders (4) connected by the air channels. The air bladders (4) are located inside the gripper fingers and are used to contact and push the gripped object. The air channels (3) are connected to an air source through air tubes (5). The air source is used to supply air to the air cavity structure. The air bladders (4) undergo controllable deformation under the drive of the air source and can coordinately adjust the posture of the gripped object relative to the gripper.

2. The apparatus according to claim 1, characterized in that, Each finger clip has at least three airbags (4) on its inner side, arranged along the length of the finger clip.

3. The apparatus according to claim 2, characterized in that, Among the airbags (4) arranged along the length of the finger, there is at least one support airbag located in the middle area and adjustment airbags located on both sides of the support airbag.

4. The apparatus according to claim 1, characterized in that, The airbag (4) is attached to the inside of the gripper fingers by an adhesive method.

5. The apparatus according to claim 1, characterized in that, The channel layer (2) is made of a flexible elastic material, including silicone.

6. The apparatus according to claim 1, characterized in that, The device includes a control unit, which is communicatively connected to an air source and is used to control the air source to supply air to the airbag (4) according to the gripper's target posture command.

7. The gripper pneumatic adjustment method of the gripper pneumatic adjustment device according to claim 6, characterized in that, Includes the following steps: The pneumatic adjustment device of the gripper is fixed to the inside of the gripper's fingers; the gripper is controlled to hold the object so that the object surface contacts the airbag (4); the control unit controls the air source to supply air to the airbag (4) based on the target posture set for the object, so that the airbag (4) deforms and pushes the object to adjust to the target posture. The control unit has a kinematic model of the mapping relationship between the airbag deformation and the object posture.

8. The method according to claim 7, characterized in that, The control unit obtains the target deformation of each airbag (4) based on the target posture and kinematic model; generates the gripper target posture command based on the target deformation, controls the air source to output the corresponding air pressure, and drives the corresponding airbag (4) to deform to the target deformation.

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